1. Field of the Invention
The present invention relates to a golf club head. More specifically, the present invention relates to a golf club head having a plurality of grooves.
2. Description of the Related Art
The prior art discloses various methods to manufacture golf club heads, especially iron-type golf club heads. For example, Rogers, U.S. Pat. No. 4,027,885 for Golf Iron Manufacture, discloses scoring grooves into a face for the club head.
Taylor, U.S. Pat. No. 4,077,632 for a Lined Face For A Golf Club discloses grooves in compliance with the Rules of Golf at that time.
Ribaudo, U.S. Pat. No. 4,529,203, for Golf Club discloses a golf club face having grooves to eliminate the slice or the hook of the golf ball.
Shira, U.S. Pat. No. 4,768,787, for a Golf Club Including High Friction Striking Face discloses grit blasting the horizontal grooves to provide a friction generating surface when the striking surface of the golf club head engages a ball. The metallic matrix of the golf ball striking face contains hard particles which are harder than the metallic matrix and protrude above the surface.
Stuff, U.S. Pat. No. 5,354,059, for Golf Club Heads With Means For Imparting Corrective Action, discloses a club head with at least two non-parallel sets of grooves.
Doolen, U.S. Pat. No. 6,179,725, for a Golf Club Having Angular Grooves discloses grooves oriented at various angles. The plurality of grooves across the golf club face are angled at an angle that is substantially non-parallel with the club sole. All grooves however are sloped in the same direction as one another.
Hirota, U.S. Pat. No. 6,193,615, for a Head Of Golf Clubs That Spins More, discloses a face having grooves that allow for pressure to act specially on the edges of the grooves to increase ball spin.
Vokey et al, U.S. Pat. No. 7,473,187, for Spin Milled Grooves For A Golf Club, discloses machining grooves into a face.
Hettinger et al., U.S. Pat. No. 7,452,283, for a Putterhead With Dual Milled Face Pattern, discloses milling grooves into a face of a putter.
Kennedy, III, U.S. Pat. No. 7,179,175, for a Golf Club Having Stepped Grooves, discloses a golf club head with V-shaped and U-shaped grooves.
U.S. Patent Application Publication Number 2009/0264217 to Johnson et al., for Golf Club Head Having a Grooved Face, discloses a spin milling or fly cutting method for forming grooves. This manner allows for tighter draft angles, increases the rate of production, and allows for tighter tolerances than casting or forging.
U.S. Patent Application Publication Number 2009/0247318 to Ban et al., for Golf Club Head, discloses a plurality of striations formed on the face and extending from a toe side to a heel side, where the cross sectional shape of each striation is a triangle asymmetric with regard to the a virtual center line in a width direction and the smallest interior angle of the three interior angles of the triangle being placed at the sole side of the golf club head.
Although these inventions have provided novel methods for forming grooves on the face of the golf club head, the prior art has not optimized groove formation.
Scoreline designs generally have a cross-section geometry that includes two edges, two side walls and a bottom. The side walls are at a predetermined angle from a vertical line. Usually, each wall has more than one section and those sections are straight or curved. Alternatively, the scoreline design is a “V” shape, in which case there is no bottom other than a vertex or fillet radius.
Iron-type golf clubs having scorelines with sharp edges and relatively vertical side walls are advantageous to golfers since such sharp edged grooves allow golfers to induce higher levels of spin on a ball struck with such an iron-type golf club having sharp edged grooves. Iron-type golf clubs without sharp edged grooves or essentially vertical side walls will induce less spin when impacting a golf ball, especially higher-lofted (40 degrees +) golf clubs.
The following requirements apply to apply to the collective ser of grooves on any individual club head. Groove width (W) is measured per the USGA 30° method. Less than 50% of groove widths shall be greater than 0.035 inch and no single groove width shall be greater than 0.037 inch. Groove widths shall not vary by more than 0.010 inch from narrowest to widest. Groove depth (D) is measured per the USGA method from adjoining land areas. Less than 50% of groove depths shall be greater than 0.020 inch and no single groove depths shall be greater than 0.022 inch. Groove depths shall not vary by more than 0.010 inch from shallowest to deepest. Groove spacing (S) is measured per the USGA 30° method. Less than 50% of groove spaces shall be less than 0.075 inch or be less than three times the width of the widest amount adjacent groove. No single groove space shall be less than 0.073 inch or be less than three times the width of the widest adjacent groove minus 0.008 inch.
For heads other than drivers and putters, the area/pitch “A/P” is measured per the USGA method from adjoining land areas. Less than 50% of A/P values shall be greater than 0.0030 inch and no single A/P value shall be greater than 0.0032 inch. For heads having loft equal or greater than 25°, the effective radius “ER” is measured per the USGA 0.0110 inch R circle method. Less than 50% of the grooves shall have more than 10° of effective radius greater than 0.0110 inch and no single groove shall have any amount of effective radius greater than 0.0113 inch.
Backspin is the primary mechanism by which a golfer can control a golf ball upon landing after being struck. Backspin is especially important for short shots where proximity to the hole is of greater consequence to the golfer. High lofted clubs (50 degrees to 75 degrees) have grooves designs which are meant to interact with the surface of a golf ball at impact and remove debris from the contacting surface in order to increase friction and thereby impart more spin on the ball. Unlike intermediate lofts whose spin can either be increased or decreased with increased friction, the high lofted club will almost always increase spin through increased friction. Traditionally groove designs have focused on increasing the groove area underneath the golf ball at impact.